Countersinking tool



March 8, 1960 R. B. RANSOM COUNTERSINKING TOOL Filed Jan. 20, 1958IN'VENTOR. 7?

HobekfB. ansom nT-roR'NEYs.

COUNTERSINKING TOOL Robert B. Ransom, Westerly, RJ.

Application January 20, 1958, Serial No; 709,825 Claims. (Cl. 145-123)This invention relates to a tool for use in sinking the heads offasteners such as screws and the like into fibrous materials such aswood so that the fastener head will be substantially flush with'thesurface into which it is positioned or sub-flush with the surface inwhich it is positioned.

Heretofore a counter sinking tool has been in the gen eral shape of theundersurface of the head to be counter sunk and formed so as to startcutting at the center and gradually increase the size of the hole on anangle or bevel until the desired recess was provided. plishing such acounter sink splintering of the'wood is frequently encountered. Fibrousmaterials, such as wood and particularly plywood splinters very easilyand with a gradually increasing diameter or cut, fibersare easily pickedup by the edge of the tool and torn from the surface in varying extentswhich is particularly bothersome in trying to provide a fine finish on awood surface.

One of the objects of this invention is to provide a tool which may beused to prevent the surface of the fibres of the wood from being tornfrom a surface larger than the diameter of the head to be sunk therein.

Another object of this invention is to combine a tool having the abovedesirable features with a drill which will provide a hole for a screw sothat as the hole nears completion, the wood will be scored in a mannerto prevent splinterin-g beyond the head of the screw as it is forcedinto the wood. I

Another object of this invention is to provide a means for inserting thehead of a screw into wood without removing the usual material beneaththe head so that the head will compress this material'which is'somewhatresilient and there will be a firm frictional grip on the underside ofthe head of the screw preventing it from back ing out of the wood andalso providing a more secure fastening of the two pieces to be securedby providing a maximum of pressure exerted between the parts fastenedtogether.

A further object of the invention is to provide a surface which willabut against the surface of the work within the area covered by thefastener head to be inserted and limit the insertion of the tool intothe work thus avoiding scratching or indenting the surface outside ofthe circle of the head of the fastener.

Another object of the invention is to providealimiting surface with aportion cut away which will serve to relieve the chips from the drillwith which the tool is combined permitting the chips to pass frombeneath the limiting surface and thus make unnecessary an addedoperation of clearing such chips as the drill and circle sink areinserted into the work.

Another object of the invention is to provide an internal depth stopwhich may be adjusted as to the sensitiveness required for stopping byreason of the area which is provided for contacting the surface of thework. A further object of the invention and a secondary object of theforming of a relief in the limiting surface is to permit the tool to actas a counter bore by the use In accom 2,927,614 Patented Mar. 8, 1960ice of a pressure on thetoolso that the fibrous materia which is of aresilient nature will be compressed beneath the limiting surface leavinga portion at the relieved area. to spring upwardly into the relief spaceof the tool and thus be in a position to be scraped by the edge adjacentthe. relief for further insertion of the tool into the wood in whichcase the tool then acts as a counter bore for such length of time as thewood compressing pressure is provided on the tool, thus making itpossible to sink'the head of a screw orfastening beneath the surface toany desired extent.

Another object of the invention is to provide a depth stop withoutclearance or relief from a cutting standpoint but which is cut away toprovide chip clearance'relief and afford a scraping action on theportion of the work which is to be removed or concealed by the head ofthe fastening.

Another object of the invention is to provide a tool which may beutilized for forming a hole at an angle to the surface which it is topenetrate without slipping or marring the surface into which it isinserted.

With these and other objects in view, the invention Figure 2 is asectional'wiew illustrating the tool as combined with a bit and with thelimiting surface in its simplest form; i Figure 3 is an elevational viewillustrating the tool as combined with a bit but with the limitingsurface cut away so that the chips from the bit may be removed by thetool action. Figure 4 is a section on line 44 of Figure 5; Figure 5 is asection on line 55 of Figure 3;

Figure 6 is a view similar to Figure 3 showing an ele-' vation of thetool and in a still different modifiedfform. and as combined to a bit;Figure 7 is a section on line 7- 7 of Figure 6; Figure 8 is a section online 8-8 of Figure 7;

Figure 9 is an elevational view. of a still different modified form oftool combined with a bit; Figure 10 is an elevation on substantiallyline 10--10 of Figure 9;

Figure 11 is a section on line 11-11 of Figure 9; Figure 12 illustratestwo blocks of wood drilled for the reception of a fastening with theupper block scored as would occur with the use of a bit and tool such asshown in Figures 1-11;

Figure 13 is a view similar to Figure 12 but showing a screw aspositioned in the hole of Figure 12 and illustrating the head of a screwas sinking into the outer sur:

face of the work and a compression of the wood beneath the beveledsurface of the screwhead; and

Figure 14 is a sectional view illustrating the action of the tool suchas shown in Figures 3 11 when sufficient.

pressure is applied to the same-to compress the resilient work intowhich it is inserted.

The tool here referred to will score the surface of fibrous materialssuch as wood into which it is desired,-

to sink the head of a fastening. This surface isscore'd to limit theinsertion of this scoring edge and located such a stop inwardly of thescoring to keep the area outside of the scoring clear of abrasion. Thestop surface is cut away sufficiently so thatwhen this tool is combinedwith a bit, the chips from the bit may be passed out from beneath thestop without interfering or clogging with the stop surface. The edge ofthis relief portion is not itself relieved as is usual in tools but Ihave found that when used upon some resilient material such as wood thatpressure sutficient to compress the wood beneath the stop surface willallow the wood in the cut away portion which is not compressed to standup above the edge of this compressed area and upon rotation of the tool,although this edge is a right angle, it will scrape away thenon-compressed work sufiiciently so that the tool may be advanced intothe work to form a counter bore in the workto the depth desired.

I have also found that by not removing the stock or wood usually removedfor a counter sink but by merely scoring a circle, the wood or materialwhich is to be bound by the head of the fastener will be compressed andthe head will exert a firmer grip on this portion of the work and abetter binding between the two portions of the work to be clamped thanhas otherwise or formerly been the case and thus many advantages areobtained by the use of the construction which will hereinafter bedescribed in greater detail.

With reference to the drawings designates generally a countersinkingtool consisting of a cylindrical head 11 and a shank 12 for theinsertion into some operating instrument such as a bit brace or the likefor rotating the same. The head 11 is recessed as at 13 and providedwith a sharp chisel edge 14 by an inward bevel 15 leaving the outersurface 15 cylindrical and parallel to its axis. Some sort of a stopsurface 17 is formed at right angles to the axis and in this particularcase this stop surface is at the end of a pistonlike head 18 having ashank 19 which is positioned in the bore 20 of the shank 12, while aplug 21 threaded into this bore 20 serves to position the abutmentsurface 17 at a location with ref- 1 erence to the edge 14 to govern thedepth of scoring which it is desired shall be made in the work. Aprojection 22 is provided to enter a previously formed bore so as toguide the operation of the tool 10. The effect of the tool in operationmay be illustrated by the showing in Figure 15 where there has been abore 23 previously formed and the edge 14 is used to provide a scoring24 as shown in this view.

In Figure 2 a tool 25 having a cylindrical outer surface 26 and a bore27 receives in this bore a bit 28 where it is held by a set screw 29.The tool 25 is recessed as at 30 and provided with a sharp edge 31formed by the bevel 32 which is similar in many respects to the recess13, edge 14 and bevel 15 of the showing in Figure 1. Tool 25 is of sucha size that it may fit into a chuck or may have its upper end 33 shapedin any desired manner to fit a chuck for turning the same. This toolshown in Figure 2 may be utilized to in one operation form the hole 23in Figure 12 also the scoring 24 shown. However, it is found that chipsfrom bit 28 may get into the recess 30 and that it is necessary to blowthese chips away just prior to the edge 31 contacting the surface of thework such as shown in Figure 12.

In order to avoid the necessity of blowing the chips away from aconstruction such as shown in Figure 2. I have cut away a portion of thetool in the development shown in Figure 3 where the tool is designated35 and the cut away portion is about a quarter of the cylinder and isdesignated 36 (see also Figure 5). In this showing the tool 35 iscylindrical having a sharp lower edge 37, an internal bevel 38 and astop surface 39 similar to the stop surface 34 in the showing in Figure2. The bit 28 and its set screw 29 are the same as shown in Figure 2while the edges 40 and 41 are in planes passing through the axis of thetool and bit and are at right angles to the surface of the stop 39. Thistool shown in Figures 3-5 may be utilized in a manner similar to the useof the tool shown in Figure 2 for providing the bore 23, as shown inFigure 15, and the scoring 24 as there shown. As a pressure necessary toadvance the bit into the wood in forming the hole 23 is exerted by hand,a noticeable interruption in the progress of the bit will be felt whenthe surface 39 engages the outer surface 42 of the work while the chipswhich emanate from the bit 28 will pass out of the recess 36 and it willbe unnecessary to provide any clearing action as the tool approaches thesurface 42 for effecting the scoring 24. In this tool as in the showingin Figure 2 the upper end 43 may be of any suitable form to bepositioned in a chuck for rotating the same.

In Figure 6 the tool 45 has provided a cut away portion 46 which issubstantially one-half of the cylinder 45 as compared with substantiallya quarter of the cylinder 35 shown in Figures 3, 4 and 5. In this casethe semicylinder at the lower edge is provided with a sharp edge 47beveled inwardly as at 48 and provided with a stop surface 49. The drillas shown at St is held in a bore of the tool by a set screw 51 similarto the arrangement described in connection with Figures 2 and 3. Theedges of the cut away portions 52 and 53 are on planes intersecting theaxis of the bit and tool and are at right angles to the stop surface 49.This tool may be used to make the hole 23 and scoring 24 as shown inFigure 12 where the bit will bore the hole 23 and the edge 47 will formthe scoring 24 and as hand pressure is exerted on the hit a perceptiblechange will be noted when the surface 49 engages the surface 42 justafter the scoring is completed. However, because of the lesser surface49 than surface 39 of Figure 3, a somewhat more sensitive feel will berequired to detect this engagement. I might vary the amount of surfaceprovided for this stop still further depending upon the sensitivity ofthe operator in utilizing the tool, it being appreciated that thegreater the surface area of this stop, the more abrupt change will beprovided in the use of the tool.

In Figures 9, 10 and 11 I have shown a tool 55 which is generallycylindrical on its outer surface but is cut away at two locations 56 and57, each in substantially the amount of the cut away portion 36 ofFigure 3. The remaining cylindrical portion, however, is provided with asharp edge 58 beveled as at 59 andprovidcd with a stop surface 60 atright angles to the axis of the bit and tool. The bit in this case isthe same as in Figure 3 and is designated 28 with a binding or set screw29 to hold it within the cylindrical bore in the tool 55. Both surfaces61 and 62 about the recess 56 and surfaces 63 and 64 about the recess 57are in planes intersecting the axis of the bit and tool and theirleading edges 62 and 64 are at right angles to the stop surface 60.However, in this case a further modification is provided in that reliefis provided at 65 from the stop surface on the trailing portion thereofwhich serves to further reduce the stop surface 60 which is provided.This tool may likewise be utilized to provide the hole and scoring asshown in Figure 12 as will be apparent from the previous description.

A screw 66 having a beveled head 67 may be utilized to hold the twopieces of wood 68 and 69 as shown in Figures 12 and 13 together and itis unnecessary to remove the portion 70 of the wood (Figure 12) withinthe circular scoring 24 in order to do this. The screw 66 may bethreaded into the hole 23 and as it obtains a grip in the part 69, itshead will be drawn into the material 70 and sunken into the part 68which by reason of the scoring 24 will prevent splitting of the surface42 and as this head is drawn into the wood the material 70 will bedisplaced inwardly and compressed as at 71 beneath the beveled head ofthe screw serving to increase the friction on the under beveled surfaceof the screw and to form a very tight binding action. Further pressureexerted by the head of the-screw in turn will be transmitted to thecontacting surfaces of the parts 68 and 69 and serve to firmly bind themtogether, in fact, much firmer than had the wood 70 been removed in theusual manner to provide a counter sink for the head 67.

It is found that the combination drill and countersinking tool such asshown in Figures 3, 6 and 9 may have a still further use in the formingof a counter bore when it is desired to position the head of a fasteninga substantial distance below the surface rather than in the form shownin Figure 13 and this may be done by exerting a substantial pressureupon the tool sufiicient so that the resilient work is compressedbeneath the stop surface such as 39, 49 or 60 and by the compressing ofthis wood beneath this stop surface the wood at the location of the cutaway portions 36, 46 or 56 and 57 will spring upwardly as shown at 73 inFigure 14 where I have illustrated a compressed portion of the wood at74 and the portion 73 extending up above the same while the surface ofthe wood is designated 75. In this case, the leading edge of therecessed portion such as 41, 53, 62 or 64 will act as a scraper and willremove this non-compressed portion ofthe wood ahead of it as it isrotated acting just like a cutter even though there is no relief of thissurface immediately atcits edge, and the tool may be forced into thewood as long as this pressure is applied by these edges'servingto scrapeaway the wood as the tool is rotated. A counter bore may be thus formedto a desired depth to serve for the receiving of the head of a fasteninga desired distance below the surface of the work.

From the above it will be apparent that I have provided a stop for theinsertion of a drill into a piece of work and at the same time a scoringoperation without the necessity of engaging the surface of the workoutside of the circle for the head of the fastener to be inserted intothe surface of the work, thus preventing marking of the. work outwardlyof this circle and at the same time I have found that I am able to sinkthe head of a fastener into a surface thus scored but withoutcounter-sinking the surface before the head of the fastener is impressedinto the surface which I have not heretofore been able to do withoutsplintering.

I claim:

1. A tool for use in sinking the head of a fastener. into the surface offibrous material comprising a body of a portion of a cylinder with anaxially extending projection at its end, the end of the body providingan abutment surface generated by the revolving of at least a portion ofa radius line disposed at an angle to the axis of said body, theabutment surface being bounded by a surface generally in a plane passingthrough the axis of the body and by a thereof.

"2. A tool as in claim 1 wherein said radius line is at 7 right anglesto the axis of said body.

3. A tool as in claim 1 wherein said cutting edge is formed by aninclined surface extending from said abutting surface to said cuttingedge.

4. A tool as in claim 1 wherein the body is provided with a plurality ofportions of a cylinder thereby provid ing a plurality of similarabutment surfaces.

5. A tool as in claim 1 wherein the body at its lower edge is aninterrupted annulus and additional cutting edges are provided along theinner edges of the portions of the annulus.

References Cited in the tile, of this patent Switzerland Aug. 1, 1953cutting edge along the periphery

